SOME of the Victoria’s worst criminals are school-aged and convicted of crimes so brutal they could still be behind bars in their late 20s.

At least four teens have been sentenced to more than a decade in custody in Victoria since July 2007.

One 16-year-old is serving 13 years for rape. Two 17-year-olds will spend more than 10 years in jail after being convicted of murder. Three teens are serving sentences between five and 10 years for manslaughter.

One disturbing incident ­involved three boys aged 14, 16 and 17, who raped a 21-year-old mother in her home and were seen laughing together when sentenced in court in 2012.

Juvenile offenders accounted for 162,000 arrests in Victoria during the past five years, with serious offences such as rape and assault on the rise.

Most of the crimes go unreported in the media because of strict court protocols protecting the identities of juveniles.

RMIT criminologist adjunct professor John Van Gron­ingen said despite the number of arrests declining, the severity of the crimes were increasing due to widespread use of ‘‘psychotropic drugs’’ and ice, and called for violent young offenders to be named.

“With rare exceptions, such as the case of rape, where the victim can be identified, I think society needs to know who has committed these offences,’’ Prof Van Groningen said.

“Will this have a deterrent effect? The jury is still out on that, but society deserves to know who is committing these violent crimes.”

Under Victorian legislation, unless tried as an adult, a juvenile offender faces a maximum sentence of three years.

They are housed in a juvenile justice centre and moved to an adult prison after turning 18.

In extreme cases, offenders as young as 16 have been held in solitary confinement in adult jails because they were too violent with centre staff and other inmates.

The growing problem has been flagged as an important issue in Victoria with police ­revealing a teenage gang called Kill Your Rivals was terrorising Melbourne in 2013.

The group — with members as young as 13 — was believed to be responsible for 80 per cent of the crimes investigated by the police specialist armed robbery taskforce.